Lithium-borovanadate glass for use in a secondary electrode

ABSTRACT

Glass particularly suitable for use in a secondary emission electrode and comprising Li2O, V2O5, B2O3 and possibly CaO and SiO2, the composition in % by weight satisfying the following conditions: 10 &lt; V2O5 &lt; 56 25 &lt; B2O3 &lt; 75 32 &lt; (B2O3+SiO2) &lt; 75 9 &lt; (Li20+ CaO) &lt; 28 (Li20+ CaO) &lt; 44/35 (B2O3+ SiO2) - 26.

United States Patent 1191 Trap Dec. 4, 1973 [54] LITHIUM-BOROVANADATE GLASS FOR 3,258,434 6/1966 MacKenzie et al 252/519 USE IN A SECONDARY ELECTRODE 3,278,317 10/1966 Blair et a1. 106/47 R 3,520,831 7/1970 Trap 106/47 R [7 51 Inventor: Hendrikus Johan Lodewijk Trap,

Emmasingel, Netherlands FOREIGN PATENTS 0R APPLICATIONS [73] Assignee: U. S. Philips Corporation, New 8,704 11/1907 Great Britain 106/47 R York, NY. 744,947 2/1956 Great Britain 106 47 R [22] Filed: Nov. 11, 1971 Primary Examiner-A. B. Curtis [21] Appl 1979 Assistant Examiner-Mark Bell Related us. Application om Ammey-Frank Trifari [63] Continuation of Ser. No. 862,446, Sept. 30, 1969,

abandoned.

[ ABSTRACT 30 F A lication Prio Data 1 0c th I ds nty 6814050 Glass particularly suitable for use in a secondary emise sion electrode and comprising L1 0, V 0 B 0 and ossibly C210 and SiO,, the composition in by [52] US. Cl. 106/54, 106/47 R, 252/521 p 51 Int. Cl C03C 3/14, 1101b 1/06, C03C 3/30 ig l s'g 'f g 58 Field of Search 106/47 R, 47 Q, 54; 25 75 1 32 (B O +S10 75 9 (Li 0+CaO) 28 [561 Reierences (Li O-l-CaO) 44/35 B,o,+si0, 26.4

UNITED STATES PATENTS 3,061,752 10/1962 Banks 106/47 R 2 Claims, N0 Drawings LITHIUM-BOROVANADATE GLASS FOR USE IN A SECONDARY ELECTRODE This is a continuation, of application Ser. No. 862,446, filed Sept. 30, 1969, now abandoned.

of glass for this purpose known from the French Patf Specification 1.509.628 is a phosphovanadate glass. The drawback of this kind of glass and the kind of glass described above is the cumbrous and time-consuming technique of providing a thin layer.

The invention relates to a range of glass compositions which are eminently suitable for use in a secondary The secondary emission multiplication in the channels is effected in the following manner. There are comparatively few electrons which travel undisturbed from one side of the channel to the other without striking the wall. In addition to a forwardly directed velocity component, the other electrons have also a laterally directed velocity component which causes them to strike the wall one or more times when travelling through the channel. In the relevant electrode the walls of the said channels consist of a substance which has the property of being secondarily emissive so that two or more electrons are released at every impact. In this manner the density of the electrons which leave the electrode is considerably increased relative to the density of the electrons impinging upon the electrode.

To maintain a uniform voltage distribution along the electron paths it is necessary that sufficient electrons are supplied by the voltage source to replace the secondary electrons which are removed. The specific resistance of the material must, however, not be so low that a noticeable increase in temperature occurs.

The present invention provides a class of glasses which have the right level of specific resistance, an emission factor of more than one and a softening point, which is the temperature at which the viscosity is poises, is between approximately 400 and 580C. As a result, an independent processing without substrate glass is possible. As regards their specific resistance, it is of great importance that no noticeable variation of the specific resistance occurs after drawing out the invented glasses to p.

The glasses according'to the invention are character- :ized in that they comprise Li,0, 8,0 V 0 and if de sired CaO and SiO,, the contents of these components in by weight satisfying the following conditions:

32 (B 0 SiO 75 9 (Li O CaO) 28 (M 0 CaO) 44/55 (B 0 SiO 26.4

The invention will now be described with reference to Table l which gives a plurality of glasses within the range of composition of the present invention and which shows a survey of the logarithm of the specific resistance at room temperature and at 250C (log p the log rithm of the surface resistance (log H; p and H indicated in ohm cm and ohm per square respectively) and the softening point in C.

These glasses were obtained in a manner conventional in glass technology by melting a mixture of the relevant oxides and/or carbonates in an oxidizing atmosphere.

Up until now two kinds of glass have found acceptance which have a secondary emission factor of more than one at the conventional electron speed. These glasses were used as inner coatings of tubes of a soft substrate glass. In order to manufacture a secondary emission electrode, which has, a diameter of, for example, 3-10 cm and a thickness of 1-2% mm, and a plurality of apertures of approximately 10 per sq.cm at a diameter of p, the starting point is a glass tube having .a diameter of, for example, 7 mm, whose inner side is provided with a layer by means of a suspension of the powdered glass, and whose outer side has a layer of a low melting enamel. These glass tubes are drawn out in stages while heating, for example, first to 1 mm and subsequently to 40 u. The hollow fibres obtained are bundled in a jig and are collectively heated whereafter the fibres are connected together by flowing of the low melting enamel, the interstice being filled up.

One of the kinds of glass known for this purpose is a lead-bismuth glass known from British Pat. Specification 971,733 which after completion of the electrode is subjected to a reducing treatment, for example, a heat treatment in a hydrogen atmosphere. A drawback of this method is that the ultimate conductivity is difficult to reproduce due to the sensitivity of the product relative to the different pre-treatments. The other kind Tubes having a diameter of 7-7.5 mm were drawn from these glasses and the tubes were coated with a thin layer of enamel having the composition in by weight:

PbO 77.1 sio, .5 ZnO 2.0 Ano, 5.5 8,0,, 13 .4 C00 0.5

These tubes were subsequently drawn out to a diameter of 1 mm, the tubes obtained were bundled and the bundle was again drawn out to l mm. The hollow monofibre then obtained a diameter of 15 IL. Subsequently, the hollow multifibres obtained were cut to pieces of 10 cm, bundled in a jig after the ends of the multifibres had been sealed off and the assembly was heated until the low melting enamel had filled up the interstices between the fibres.

After cooling and removing the sealed ends, the hollow fibres were filled with wax and the assembly was subsequently sawn into discs having a thickness of 2 mm. Subsequently, the wax was removed from the tubes with the aid of ethyl alcohol. Finally the discs were provided with metal coatings on either side by means of vapour deposition and they could then serve as secondary emission electrodes.

TABLE I Composition (percent by weight) log 9 (p in 11 Log 11 Soften- At (11 in n) ing room At per point L120 B10; CaO S102 V temp. 250 C. square C.)

Number V203 36.6 s B 0 s 64.9 9.3 s Li O s 27 wherein said glass has a secondary emission factor greater than one and is particularly suited for use as a secondary emission electrode.

wherein said glass has a secondary emission factor secondary emission electrode.

2. Glass consisting essentially of the following in by weight:

To motivate the boundary of the range of composition, Table 11 shows a few compositions outside this 40 greater than one and is particularly suited for use as a range and states the reason why these compositions are unsuitable for use in a secondary emission electrode.

What is claimed is:

1. Glass consisting essentially of the following in by weight:

5.6 s Li O s 18.8

1.0 CaO 14.8

1.2 s SiO s 15.9

3 NITED STATES PATENT'OFFICE I CERTIFICATE OF CORRECTION Patent No; 3,776,745 Dated December 1;, 19723- Inventor(s) HENDRIKUS JOHAN o LODEWIJK TRAP It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 3, Table II, #34 under B 0 "3.10f' should read --3 l .0-

Signed and sealed this Lpth day of June 1971;.

(SEAL) Attest:

EDWARD M-FLETCHER,JR. C. MARSHALL DANN Attesting Officer Commissioner of Patents 

2. Glass consisting essentially of the following in % by weight: =b 16.4 < or = V2O5 < or = 53 36.6 < or = B2O3 < or = 64.9 9.3 < or = Li2O < or = 27 wherein said glass has a secondary emission factor greater than one and is particularly suited for use as a secondary emission electrode. 